The embodiments described herein relate generally to medical devices and methods for delivery catheters, and more particularly to delivery catheters configured for creating a passage in and/or through a target tissue for placement of a guidewire.
Many surgical procedures include delivering at least a portion of a device such as a catheter or the like to positions within a patient where access may be limited (e.g., by the anatomy or the like). For example, atrial fibrillation of a heart is typically treated by isolating portions of the atria. Such isolation of the atria can be done by open-heart surgery (e.g., a modified Maze procedure) or, most commonly, by a trans-venous catheter technique. In some known instances, the doctor cauterizes the left atrial muscle tissues using radiofrequency ablation techniques, with the ablation lesion targeting and/or circumscribing the pulmonary veins. Isolation of these anatomic portions of atria prevents the electrical propagation of the arrhythmia into the remainder of the atria. Generally, the operator (e.g., surgeon or interventionalist) places electrophysiologic catheters into the right heart. Under fluoroscopic guidance, a catheter is advanced adjacent to the atrial septum. In most cases, a puncture of the atrial septum (right to left) is made with a specialized needle catheter. A guidewire is then advanced into the left atrium.
The trans-septal catheter is removed and a guide catheter is delivered over the wire into the left atrium. An ablation catheter is then advanced into the left atrium under fluoroscopic guidance. Typically, electrophysiologists use additional imaging and mapping technology to improve safety and efficacy of the procedure, such as intracardiac ultrasound, cardiac computed tomography (CT), or non-contact mapping systems. Once the ablation/mapping catheters are in the left atrium, the operator delivers radiofrequency energy to the target sites. The operator moves the ablation catheter in a point-by-point fashion connecting the lesions, which in effect, electrically isolates the pulmonary veins from the rest of the atrium.
These known procedures typically take 3-6 hours to complete. The procedural success varies between operators and patient selection (success rate is between 50-85% for a single attempt), with some patients receiving subsequent ablation procedures to “touch up” the prior ablation site. The cost of these procedures is variable and increases substantially with duration of procedure and/or the addition of adjuvant imaging/mapping technology. Generally, current procedures are associated with a 5-6% risk of procedural complications, including a 0.5% risk of stroke due to instrumenting (i.e., placing one or more medical devices into) the left atrium. Other complications can include cardiac perforation, tamponade, pulmonary vein stenosis, and atrial-esophageal fistula. Despite attempts to simplify and streamline the procedure, the anatomic variations of the left atrium and pulmonary veins have limited the utility of alternative ablation techniques.
In some known instances, pericardial techniques for treating atrial fibrillation are employed; however, such known techniques also have various limitations. For example, most current pericardial ablation strategies include an operator blindly navigating recesses of the pericardial space with an ablation catheter. In some instances, reflections formed in the pericardial space, also described as “pericardial reflections”, can pose an obstacle to delivery of a single contiguous lesion using these techniques. Thus, the anatomy of the pericardial space limits the efficacy and technical ease of current pericardial/epicardial catheter-based procedures. For example, although the membranous reflections of the pericardial space are thin and relatively avascular, the angle, spatial limitations, and orientation of the surgical access point relative to the pericardial reflections does not facilitate simple puncture with a blunt catheter or a standard needle. Moreover, the large vessel and cardiac chambers adjacent to the pericardial reflections make the proposition of blind puncture with conventional catheters impractical.
Accordingly, there is a need in the pertinent art for devices, systems, and methods for efficiently and reliably locating and puncturing pericardial reflections, e.g., for delivery of a guidewire and/or catheter.